Surface area in the room: 4 * 3 * 2+3.5 * 3 * 2+4 * 3.5 = 24+21+14 = 59 square meters.

Minus the area of doors and windows: 59-1* 2-2 *1.5 = 59-2-3 = 54 square meters.

Paint used: 0.9 * 54 = 48.6kg.

Amount of money needed: 32*48.6= 1555.2 yuan.

Answer: Cong Cong needs 1555.2 yuan to finish painting his room.